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EclipseLink MOXy provides the ability to augment the annotation metadata with an XML bindings file. With this feature, EclipseLink can now process multiple bindings files from different locations, and create a merged set of metadata.

Sample use case: 1. Initial metadata is specified with a metadata file. 2. Second version modifies the metadata with an additional XML bindings file. 3. Subsequent versions continue to modify with additional bindings files.

With the metadata layered in this way a JAXBContext could be created to represent any version of the XML document.

By using this in conjunction with a multi-tenant architecture, you can define a base set of metadata using one XML Bindings file, and then an additional file for each tenant. This example will be based on the object model from the EclipseLink Moxy Extensibile example.

Java Model


package examples.virtual;
import java.util.HashMap;
import java.util.Map;
import javax.xml.bind.annotation.XmlTransient;
import org.eclipse.persistence.oxm.annotations.XmlVirtualAccessMethods;
public class ExtensibleBase {
    private Map<String, Object> extensions = new HashMap<String, Object>();
    public <T> T get(String property) {
        return (T) extensions.get(property);
    public void put(String property, Object value) {
        extensions.put(property, value);


The Customer class will be extensible since it inherits from a domain class that has been annotated with @XmlVirtualAccessMethods.

package examples.virtual;
import javax.xml.bind.annotation.XmlRootElement;
public class Customer extends ExtensibleBase {
    private String firstName;
    private String lastName;
    private Address billingAddress;
    public String getFirstName() {
        return firstName;
    public void setFirstName(String firstName) {
        this.firstName = firstName;
    public String getLastName() {
        return lastName;
    public void setLastName(String lastName) {
        this.lastName = lastName;
    public Address getBillingAddress() {
        return billingAddress;
    public void setBillingAddress(Address billingAddress) {
        this.billingAddress = billingAddress;


It is not necessary to have every class in your model be extensible. In this example the Address class will not have any virtual properties.

package examples.virtual;
public class Address {
    private String street;
    public String getStreet() {
        return street;
    public void setStreet(String street) {
        this.street = street;


Like Customer, PhoneNumber will be an extensible class.

package examples.virtual;
import javax.xml.bind.annotation.XmlValue;
public class PhoneNumber extends ExtensibleBase {
    private String number;
    public String getNumber() {
        return number;
    public void setNumber(String number) {
        this.number = number;